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In this work we developed electrospun lignin/cellulose acetate fiber-bead nanostructures and explored their potential as structuring agents for vegetable oils to be used as eco-friendly lubricating oleogels. A variety of nanostructures were obtained from solutions containing 20 or 30 wt. % eucalyptus Kraft lignin (EKL) and cellulose acetate (CA) in variable weight ratios from 100:0 to 60:40 in an N,N-dimethylformamide/acetone mixture. The EKL/CA solutions were characterized in physicochemical terms from viscosity, surface tension and electrical conductivity measurements. Also, the electrospun nanostructures were characterized morphologically by scanning electron microscopy. Their morphology was found to be strongly dependent on the rheological properties of the biopolymer solution. Electrospun EKL/CA beaded nanofibers and well-developed uniform nanofiber mats allowed oleogels to be easily obtained by simply dispersing them in castor oil whilst nanoparticle clusters gave rise to unstable dispersions. The rheological properties of these gel-like dispersions can be tailored through the membrane concentration and/or EKL/CA ratio and depend to a large extent on the morphology of the electrospun nanostructures. The rheological and tribological properties of the oleogels were comparable to those previously reported for conventional and other bio-based lubricating greases. Overall, electrospun EKL/CA nanofibers allow easy, efficient structuring of vegetable oils to obtain oleogels holding potential for use as lubricants., Research Project RTI2018–096080-B-C21, funded by MCIN/AEI/10.13039/501100011033 and “ERDF A way of making Europe”. PhD Research Grant PRE2019–090632 from Spain’s Ministry of Science and Innovation. Funding for open access charge: Universidad de Huelva / CBUA

El presente trabajo se centra en el desarrollo de nanocomposites de lignina kraft de eucalipto (EKL)/acetato de celulosa (CA) empleando la técnica de electrohilado, dichas nanoestructuras tienen una potencial aplicación como agente espesante para la elaboracion de grasas lubricantes. Las propiedades fisicoquímicas las distintas disoluciones elaboradas de EKL/CA se caracterizaron mediante ensayos reológicos, de tensión superficial y de conductividad eléctrica, por otro lado, las propiedades morfológicas de las nanoestructuras electrohiladas se obtuvieron mediante microscopía electrónica de barrido. Los resultados denotan que las propiedades morfologicas de las nanoestructuras electrohiladas depende principalmente de las propiedades fisicoquímicas de la disolución. Por otro lado, se llevó a cabo la caracterización morfologica, reológica y tribológica de los oleogeles obtenidos a partir de la dispersión de las membranas electrohiladas en aceite de ricino. Como resultado de dicha caracterizacion se obtuvo que las propiedades reológicas de los oleogeles pueden adaptarse modificando la relación EKL/CA y el contenido de nanocomposite empleado en la dispersión. Como conclusión general, el electrospinning de disoluciones de EKL/CA puede proponerse como un método sencillo y eficaz para producir olegeles lubricantes, con propiedades similares a las grasas convencionales., The present work is focused on the development of eucalyptus kraft lignin (EKL)/cellulose acetate (CA) nanocomposites using the electrospinning technique, these nanostructures have a potential application as a thickening agent for the production of lubricating greases. The physicochemical properties of the different elaborated EKL/CA solutions were characterized by rheological, surface tension and electrical conductivity tests, on the other hand, the morphological properties of the electrospun nanostructures were obtained by scanning electron microscopy. The results show that the morphological properties of the electrospun nanostructures depend mainly on the physicochemical properties of the solution. On the other hand, the morphological, rheological and tribological characterization of the oleogels obtained from the dispersion of the electrospun membranes in castor oil was carried out. As a result of this characterization it was obtained that the rheological properties of the oleogels can be adapted by modifying the EKL/CA ratio and the nanocomposite content used in the dispersion. As a general conclusion, the electrospinning of EKL/CA solutions can be proposed as a simple and efficient method to produce lubricating oleogels, with properties similar to conventional greases., J.F.R.-V. agradece la concesión de la beca de investigación doctoral PRE2019-090632 del Ministerio de Ciencia y Educación de España